Calculate (1/5)³: Solving the Cube of a Simple Fraction

Fraction Exponents with Power Rules

Insert the corresponding expression:

(15)3= \left(\frac{1}{5}\right)^3=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simplify the following problem
00:03 According to the laws of exponents, a fraction raised to a power (N)
00:07 equals the numerator and denominator raised to the same power (N)
00:11 We will apply this formula to our exercise
00:15 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Insert the corresponding expression:

(15)3= \left(\frac{1}{5}\right)^3=

2

Step-by-step solution

To solve this problem, we need to simplify the expression (15)3 \left(\frac{1}{5}\right)^3 using the exponent rules for fractions:

  • Step 1: Identify the base and the exponent. Here, the base is 15 \frac{1}{5} and the exponent is 3 3 .
  • Step 2: Apply the rule for raising a fraction to a power. The rule states that (ab)n=anbn \left(\frac{a}{b}\right)^n = \frac{a^n}{b^n} .
  • Step 3: Apply the exponent to both the numerator and the denominator:

Thus, (15)3=1353 \left(\frac{1}{5}\right)^3 = \frac{1^3}{5^3} .

Therefore, the simplified expression is 1353 \frac{1^3}{5^3} , which corresponds to choice 1 in the provided options.

3

Final Answer

1353 \frac{1^3}{5^3}

Key Points to Remember

Essential concepts to master this topic
  • Power Rule: Apply exponent to both numerator and denominator separately
  • Technique: (15)3=1353 \left(\frac{1}{5}\right)^3 = \frac{1^3}{5^3} keeps fraction structure
  • Check: Verify 1353=1125 \frac{1^3}{5^3} = \frac{1}{125} using basic exponent rules ✓

Common Mistakes

Avoid these frequent errors
  • Applying exponent to only the denominator
    Don't write (15)3=153 \left(\frac{1}{5}\right)^3 = \frac{1}{5^3} = incorrect result! This ignores the power rule for fractions and gives the wrong expression. Always apply the exponent to both the numerator AND denominator using (ab)n=anbn \left(\frac{a}{b}\right)^n = \frac{a^n}{b^n} .

Practice Quiz

Test your knowledge with interactive questions

\( (3\times4\times5)^4= \)

FAQ

Everything you need to know about this question

Why do I need to apply the exponent to both parts of the fraction?

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The power rule for fractions states that (ab)n=anbn \left(\frac{a}{b}\right)^n = \frac{a^n}{b^n} . When you raise a fraction to a power, you're multiplying the entire fraction by itself that many times, so both numerator and denominator get the exponent!

What's the difference between 1353 \frac{1^3}{5^3} and 135 \frac{1^3}{5} ?

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1353=1125 \frac{1^3}{5^3} = \frac{1}{125} is correct because both parts get cubed. 135=15 \frac{1^3}{5} = \frac{1}{5} is wrong because the denominator wasn't cubed. Always apply the exponent to both numerator and denominator!

Can I just multiply 15×15×15 \frac{1}{5} \times \frac{1}{5} \times \frac{1}{5} instead?

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Yes! That's exactly what the power rule does. 15×15×15=1×1×15×5×5=1353 \frac{1}{5} \times \frac{1}{5} \times \frac{1}{5} = \frac{1 \times 1 \times 1}{5 \times 5 \times 5} = \frac{1^3}{5^3} . The power rule is just a shortcut for repeated multiplication!

Why does 13 1^3 still equal 1?

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Any power of 1 always equals 1! So 13=1×1×1=1 1^3 = 1 \times 1 \times 1 = 1 . This is why (15)3=1353=153=1125 \left(\frac{1}{5}\right)^3 = \frac{1^3}{5^3} = \frac{1}{5^3} = \frac{1}{125} .

How do I know when to leave the answer as 1353 \frac{1^3}{5^3} versus 1125 \frac{1}{125} ?

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Check what the question asks for! If it wants the expression form (showing the work), leave it as 1353 \frac{1^3}{5^3} . If it wants the simplified numerical answer, calculate to get 1125 \frac{1}{125} .

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